A multi-compartment syringe, allowing the user to store multiple components of a medicament in separate, individually sealed compartments until ready for use is known in the art. A multi-compartment syringe comprising a single multi-compartment barrel, is disclosed in U.S. Pat. No. 6,743,194, herein “the '194 patent”, which is assigned to the assignee of the present application and whose contents are incorporated by reference. In the '194 patent, the syringe is a single barreled syringe that may be configured to store two or more components of a medicament or other formulation separately in hermetically sealed compartments until just prior to use. When ready to mix the contents of the pre-filled syringe, the seal(s) partitioning the compartments can be easily unsealed, establishing a two-way flow communication between the compartments so that the contents of each compartment can be mixed to form the medicament.
Thus, the '194 patent describes and claims a syringe including a syringe body having an opening at each of its top and bottom ends; a shoulder provided between the top and the bottom ends defining a top-compartment sidewall portion between the top end and the shoulder; the shoulder further defining a bottom-compartment sidewall portion between the shoulder and the bottom end; the bottom-compartment sidewall portion having a larger cross-section than the top-compartment sidewall portion; a plunger having a shaft, a distal end, a proximal end, and a plunger head having a smaller cross-section than the bottom-compartment sidewall portion provided at the distal end; the plunger inserted into the syringe body plunger head first through the bottom-end opening; the plunger head configured and adapted to form a seal when the plunger head engages the top-compartment sidewall, wherein the plunger is axially translatable between a first position where the plunger head is sealingly engaged with the top-compartment sidewall dividing the syringe body into a top compartment and a bottom compartment, and a second position where the plunger head disengages from the top-compartment sidewall establishing a two-way flow communication between the top and bottom compartments; and a bottom closure member having a central aperture in which the plunger shaft is slidably disposed, wherein the bottom closure member is slidable along the plunger shaft between an unsealed position where the bottom-end opening is not sealed and a sealed position sealing the bottom-end opening of the syringe body.
The syringe according to the '194 patent may be used to form a multi-compartment container for storing a variety of medicaments as, for example, medicaments for human use in the form of a dry powder which are mixed with a liquid to form a liquid formulation shortly, before use. Such medicament, for example, may include a variety of drugs, e.g. antibiotics. The shelf life of such mixed dry powder and liquid formulations is limited, and this dictates the need to prepare the formulation only shortly before use. The limited shelf life of the powder and liquid formulation is a result of a loss of activity of an active ingredient in the formula, accelerated oxidation once in solution, etc.
While this syringe has various advantages over conventional syringes, it is a single barreled syringe, requiring either that the compartments be filled in a single location or by the user at the time of use. Additionally, filling the separate compartments of this syringe with different components is cumbersome and limited. Furthermore, it has little flexibility, as in cases where one component may be mixed on one occasion with a second component, while on another occasion, it is preferred to mix the first component with a different component altogether. In addition, if an additional component is required to be added it is not possible to add another compartment to a prepared syringe of defined size and volume.
Another disadvantage of the single body syringe of the '194 patent is the method of filling the syringe. The syringe is assembled and filled, according to one method, by first orienting the body with the two-compartment embodiment of the syringe in an upright position with its top-end opening pointing upwardly. The plunger is then inserted into the syringe body, plunger-head portion first, until the plunger head engages the top-compartment sidewall. This forms a hermetic seal at the bottom of the top compartment near the shoulder portion. The top compartment is then filled with a first component of a medicament, preferably a liquid, through the top-end opening and sealed with a suitable top sealing member or assembly.
Alternatively, the top compartment may be filled by inserting the plunger completely to the end of the top compartment, immersing the open top end in the liquid, then drawing the liquid into the top compartment by pulling the plunger back to its sealed position between the compartments. This method is only practical when the first component of the medicament is a liquid.
Next, the syringe device may be turned 180 degrees, with the sealed top end oriented downwardly, so that the bottom-end opening is facing up. The bottom compartment is filled with a second component of the medicament through the bottom-end opening and sealed with the bung. Filling the bottom compartment while the plunger shaft is disposed through the bottom-end opening is cumbersome and poses various constraints on the filling process. The second component may be a liquid or a powdered solid substance. In this embodiment where a bung seals the bottom opening, the second component may be placed in the bottom compartment in a hydrated form and dried using a lyophilization process.
There is a design concern with the prior art multi-compartment syringes that, prior to use, the compartments be hermetically sealed, so as to prevent, over an extended period of time, accidental pre-mature mixing of liquid or liquid vapor of a component in one compartment with a component in a second compartment. Another design concern with such multi-compartment syringes is that the user should be able to readily inspect the component in any of the compartments just prior to use, in order to verify its useful condition. Yet another concern with many of the multi-compartment syringes is the relatively high cost of manufacture.
Accordingly, it would be very desirable to have a multi-compartment syringe which is formed of two or more separate containers capable of separately storing one or more different components, and which can be joined together as desired, depending upon the components required, and which can farther be extended in situ, if additional components are required. Advantages of such a multi-compartment syringe include the possibility of filling the compartments in different locations and assembling the syringe where and when needed. Additionally, the filling of the separate containers, each having top and bottom sealable openings, is a much easier and more flexible task. Because each component of a multi-component medicament may be stored in separately sealed containers, the components of a medicament may be stored for longer periods without concerns of accidental mixing. The use of such a syringe may also shorten the time required for administering a medicament which is a solution of two components. Each of the assembly units may be provided in various sizes to accommodate different quantities of each component of a medicament, where appropriate. In particular, the dispensing unit may have a pre-selected volume permitting multiple injections of a pre-selected dose of a medicament. In this case, the medicament may be stored in the plunger unit whereas the dispensing unit may have a pre-selected volume permitting multiple injections of a pre-selected dose of a medicament, which is transferred from the plunger unit into the dispensing unit just prior to injecting of the pre-selected dose.